2014-2015
Logic Design
Lab 9
Binary Counters
•
Counters are a specific type of sequential circuit.
•
an n-bit binary counter consists of n flip-flops (FF) and can count in binary
from 0 through 2n - 1
•
•
Binary counters use flip-flops in complementing mode, such as:

T flip-flop with T=1

JK flip-flop with J=K=1

D flip-flop with D=Q'
Binary counters have two types, ripple counter and synchronous counter.
Ripple Counter

This counter is called asynchronous because not all flip-flops are hooked to the same
clock.

The first FF is triggered by a clock pulse while the remaining FFs are triggered by the
output of the preceding FFs.
Task:
It is required to design 4-bit binary ripple counter
Steps:

Use 4 D flip-flops connected such that when C input of each FF is enabled, the FF
complements its state.

A0 (represent the least significant bit): complement its state every clock cycle

A1: complement its state every time A0 goes from 1 to 0 (negative edge)

A2: complement its state every time A1 goes from 1 to 0 (negative edge)

A3(represent the Most significant bit): complement its state every time A2 goes
from 1 to 0 (negative edge)
2014-2015
Logic Design
A3
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
A2
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
A1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
A0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
2014-2015
Logic Design
2014-2015
Logic Design
Task 1
To build the ripple Counter in Atanua, we already used the example of BDC decoder which
exists in  Atanua folder/tests/7447.atanua. Update the circuit 7447.atanua to take its input
from the ripple counter as the following figure.
2014-2015
Logic Design
Task 2
Build a game consists 8 lamps. In every period one of them (8 lamps) shouldn’t be light. A
player should catch first lamp when first lamp is dark by pressing on button 0. There a Lamp
detect that user catch it or not. You can Change speed of moving dark lamp through using a
Clock.
Build These Circuit by using 3-bit Ripple counter, 3-bit Decoder, D-Flip-flop
As Figure